Objectives: Analyzing preoperative parameters to help determine the risk of a random or systematic prostate needle biopsy specimen detecting an incidental microscopic prostate cancer.
Methods: We reviewed the charts of 28 patients who had < or = 3 mm of Gleason grade (Glgr) < or = 2 (score < or = 4) prostate cancer in their prostate biopsy specimen and subsequently underwent a radical retropubic prostatectomy (RRP). Histopathologic review of the RRP specimen was carefully performed to determine the respective tumor volume, number of tumor foci, pathologic stage, Glgr, and score. Prostate-specific antigen (PSA) levels and the calculated PSA density (PSAD) were recorded for each case.
Results: Sixteen of the 28 (57%) RRP specimens contained a very small well-differentiated tumor (< or = 0.2 cc); 7 (25%) tumors were minimally larger (0.2 to 0.5 cc); and 2 specimens (7%) contained a large tumor (4 and 6 cc) only sampled by the biopsy specimen. Mean PSA levels and PSAD values both significantly differentiated tumors < or = 0.5 cc from those > 0.5 cc (p < 0.005). PSA < or = 4 vs PSAD < or = 0.1 correctly identified 12 of 23 (52%) vs 22 of 23 (96%) tumors < or = 0.5 cc, and 10 of 16 (63%) vs 15 of 16 (94%) tumors < or = 0.2 cc, respectively; both parameters excluded 4 of 5 (80%) tumors > 0.5 cc. PSA < or = 4 vs PSAD < or = 0.1 identified 13 of 25 (52%) vs 24 of 25 (96%) organ-confined tumors, respectively, and both parameters excluded the 2 specimen-confined and 1 margin-positive tumors. Thus, PSAD had an excellent ability to differentiate the tumors based on their volumes. All tumors < or = 0.5 cc in the RRP specimen were organ-confined and postoperative serial PSA levels remained < 0.4 in these patients at a mean follow-up of 24 months.
Conclusions: Our data indicate that a patient who has a random or systematic prostate biopsy specimen that contains < or = 3 mm of Glgr < or = 2 prostate cancer and a PSAD < or = 0.1 is at a substantial risk (82%) of being diagnosed with an incidental, organ-confined, and probably insignificant, microscopic prostate cancer.